Browse publications by year: 2023

Fulltext DFT Studies of the Photocatalytic Properties of MoS2-Doped Boron Nitride Nanotubes for Hydrogen Production

Itas YS, Suleiman AB, Ndikilar CE, Lawal A, Razali R, Ullah MH, et al.

ACS Omega, 2023 Oct 17;8(41):38632-38640.
PMID: 37867711 DOI: 10.1021/acsomega.3c05907

This study investigated the photocatalytic properties of MoS2-doped boron nitride nanotubes (BNNTs) for overall water splitting using popular density functional theory (DFT). Calculations of the structural, mechanical, electronic, and optical properties of the investigated systems were performed using both the generalized gradient approximation and the GW quasi-particle correction methods. In our calculations, it was observed that only (10, 10) and (12, 12) single-walled BNNTs (SWBNNTs) turned out to be stable toward MoS2 doping. Electronic property calculations revealed metallic behavior of (10, 10)-MoS2-doped SWBNNTs, while the band gap of (12, 12) SWBNNT was narrowed to 2.5 eV after MoS2 doping, which is within the obtained band gaps for other photocatalysts. Hence, MoS2 influences the conduction band of pure BNNT and improves its photocatalytic properties. The water-splitting photocatalytic behavior is found in (12, 12) MoS2-doped SWBNNT, which showed higher water oxidation (OH-/O2) and reduction (H+/H2) potentials. In addition, optical spectral calculations showed that MoS2-doped SWBNNT had an optical absorption edge of 2.6 eV and a higher absorption in the visible region. All of the studied properties confirmed MoS2-doped SWBNNT as a better candidate for next-generation photocatalysts for hydrogen evolution through the overall water-splitting process.
New Mathematical Technique for Step Rate Test Analysis Aids Determination of Fracture Pressure and Overcomes the Uncertainty of Conventional Analysis

Mandal D, Elraies KA, Jufar S

ACS Omega, 2023 Oct 17;8(41):38313-38329.
PMID: 37867727 DOI: 10.1021/acsomega.3c04690

Experience in the oil industry has shown that it is challenging to sustain successful long-term matrix injection, as injection water quality cannot be maintained rigorously due to facility hiccups and membrane clogging. Most oil field operators have resolved this problem of injectivity decline by increasing the surface injection pressure to part the formation and inject just above the fracture gradient with strict offtake management for zonal conformance. This is not an easy task as injection much above fracture opening pressure can lead to water fingering and poor sweep that results in uneconomical waterflood recovery. The operators, thus, strive to inject at a pressure just above the fracture opening pressure so that the fracture opens near the wellbore but does not extend and then maintain the pressure just above the fracture closing pressure. Therefore, determination of the fracture opening pressure and fracture closing pressure has remained critical data for the success of waterflood projects. The most reliable industry approach to estimating fracture opening and fracture closing pressures comes from the step rate test (SRT). This traditional approach of Cartesian analysis of pressure-rate plot fits straight lines through the data in a plot of injection pressure against injection rate and then estimates the fracture pressure from the intersection of these lines having different slopes. The data received often do not exhibit one clear change in slope, thus resulting in multiple possible solutions, making it difficult for the operator to use the data for high CAPEX facilities design. Most past studies indicate the subjectivity of this Cartesian slope fitting technique. Alternative solutions through multirate superposition analysis found limited application in the analysis of SRT data due to considerable sensitivity to the value of initial pressure used for superposition and lack of stability of rate and pressure data. In this article, a new technique of SRT analysis is presented, which provides a unique solution for fracture opening and fracture closing pressures. It helps to overcome the limitations of the traditional technique of arbitrary fitting of straight lines. It uses the mathematical understanding of cumulative derivatives to recognize that the matrix opens when the cumulative growth of the rate of injectivity shows a change. It estimates the derivative of the injection rate with respect to injection pressure at each step. Then, it estimates the fracture pressure from the plot of the cumulative of this derivative against pressure at each step. It helps to overcome the challenge SRT solutions posed by the nonlinear trend of pressure data at each injection step both before fracture and after fracture is initiated. It also overcomes the limitations of the multirate superposition technique, as it is not sensitive to the value of initial pressure used for superposition.
Fulltext Large-scale sporting events during the COVID-19 pandemic: insights from the FIFA World Cup 2022 in Qatar with an analysis of patterns of COVID-19 metrics

Dergaa I, Ben Saad H, Zmijewski P, Farhat RA, Romdhani M, Souissi A, et al.

Biol Sport, 2023 Oct;40(4):1249-1258.
PMID: 37867752 DOI: 10.5114/biolsport.2023.131109

The 2022 FIFA World Cup (FIFA-WC) held in Qatar presented unique challenges, given the potential for rapid transmission of coronavirus disease 2019 (COVID-19) among over 1.4 million international fans attending the event. This study aimed to investigate the impact of the FIFA-WC 2022 on COVID-19 cases, deaths, and reproduction rate (R0) in Qatar. Additionally, it sought to understand the implications of hosting large-scale events during a pandemic without COVID-19 restrictive measures, providing critical insights for future decision-making. Data from "Our World in Data" were analysed for three distinct periods: one week before the FIFA-WC (week-preWC), the four weeks of the event (week-1WC to week-4WC), and one week after (week-postWC). The results revealed a significant increase in COVID-19 cases during week-3WC and week-4WC (compared to week-preWC) in Qatar, followed by a subsequent decrease during the week-postWC. Notably, Qatar experienced a more pronounced surge in positive cases than the global trend. Regarding COVID-19-related deaths, Qatar's peak occurred during week-2WC, while globally deaths peaked from week-3WC to week-postWC. Nevertheless, Qatar's death toll remained relatively low compared to the global trend throughout the event. The findings highlight that the FIFA-WC 2022 in Qatar demonstrated the feasibility of organizing large-scale sporting events during a pandemic with appropriate measures in place. They emphasize the importance of high vaccination coverage, continuous monitoring, and effective collaboration between event organizers, healthcare authorities, and governments. As such, the event serves as a valuable model for future gatherings, underlining the significance of evidence-based decision-making and comprehensive public health preparedness.
Fulltext Physicochemical properties and density functional theory calculation of octahedral UiO-66 with Bis(Trifluoromethanesulfonyl)imide ionic liquids

Majid MF, Mohd Zaid HF, Abd Shukur MF, Ahmad A, Jumbri K

Heliyon, 2023 Oct;9(10):e20743.
PMID: 37867795 DOI: 10.1016/j.heliyon.2023.e20743

In this study, the physicochemical properties and molecular interactions between zirconium-based metal-organic framework (UiO-66) and three different ionic liquids based on bis(trifluoromethanesulfonyl)imide anion (EMIM+, BMIM+ and OMIM+) was performed via a combined experimental and computational approach. The ionic liquid loaded UiO-66 or IL@UiO-66 was synthesized and characterized to understand the host-guest interaction. Density functional theory calculation was performed to analyse the electronic structure of IL@UiO-66 to provide molecular insight on the dominant interactions occurred in the hybrid material. Results showed that all ILs were successfully incorporated into the micropores of UiO-66. The 3D framework was retained even after loaded with ILs as analyzed from XRD pattern. FTIR spectrum reveals that interactions of ILs with UiO-66 influenced by the alkyl chain length of the cation. The anion has a profound affinity with the UiO-66 due to the presence of electronegative atoms. Phase transition study from DSC suggested that the incorporation of ILs has stabilized the framework of UiO-66 by shifting the endothermic peak to a higher state. These findings were further elaborated with DFT calculation. Geometrical optimizations confirmed the structural parameter changes of UiO-66 when loaded with ILs. These was mainly contributed by the non-covalent interactions which was confirmed by the reduced density gradient scattered plot. Another important findings are the strength of hydrogen bonding at the host-guest interface was influenced by the alkyl chain length. The molecular orbital analysis also shows that the size of alkyl chain influence the reactivity of the hybrid material. The present study provides fundamental insights on the molecular interaction of UiO-66 and ILs as a hybrid material, which can open new possibilities for advanced material for metal-organic framework applications in energy storage system, catalysis, gas storage and medicinal chemistry.
Viscous dissipation effects on hybrid nanofluid flow over a non-linearly shrinking sheet with power-law velocity

Waini I, Alabdulhady S, Ishak A, Pop I

Heliyon, 2023 Oct;9(10):e20910.
PMID: 37867886 DOI: 10.1016/j.heliyon.2023.e20910

This research intends to investigate the effect of the nonlinearity of the surface velocity on the hybrid nanofluid flow behavior. Here, the total composition of Al2O3 (alumina) as well as Cu (copper) volume fractions, are implemented in a one-to-one ratio and then dispersed in water. The similarity equations are gained employing a similarity transformation, which is programmed in MATLAB software. The dual solutions are attainable for certain ranges with respect to the mass flux parameter S and the power-law index n. Also, the turning point occurs in the region of S<0 and n>1. Besides, the rise of n led to reduce the skin friction as well as the heat transfer coefficients with 39.44 % and 11.71 % reduction, respectively. Moreover, 14.39 % reduction of the heat transfer rate is observed in the presence of viscous dissipation (Eckert number). It is found that only the first solution is stable as time progresses. Generally, this study gives scientists and engineers a starting point for predicting how to control the parameters to achieve the best results for relevant practical applications.
Fulltext The effects of anthropogenic disturbance and seasonality on the ant communities of Lang Tengah Island

Yek SH, Sethu Pathy T, Yeo DYC, Gan JYS

PeerJ, 2023;11:e16157.
PMID: 37868047 DOI: 10.7717/peerj.16157

Anthropogenic disturbances and seasonal changes significantly impact diversity and community composition of ants, but their effects are often intertwined. We investigated these drivers on Lang Tengah Island, a location with a pronounced monsoon season and three resorts that close during this period. We surveyed four sites, two disturbed and two undisturbed, before and after the monsoon season, using pitfall traps to sample epigaeic ant communities. Undisturbed habitats had higher species diversity, but both habitats (undisturbed and disturbed sites) have a high proportion of ants with characteristics of being encroached by generalist and invasive/tramp ant species. Post-monsoon sampling yielded an increase in species richness and diversity. Seasonal changes, such as monsoonal rains, can temporarily alter ant interactions and resource distribution, potentially maintaining diversity. Future studies should validate these findings for ant communities under similar pressures, using ant composition and functional roles for conservation and management purposes.

MeSH terms: Animals; Ants*; Seasons; Ecosystem; Introduced Species
Fulltext A systematic review on physical mutagens in rice breeding in Southeast Asia

Baadu R, Chong KP, Gansau JA, Mohamed Zin MR, Dayou J

PeerJ, 2023;11:e15682.
PMID: 37868055 DOI: 10.7717/peerj.15682

In the 1920s, Lewis Stadler initiated the introduction of permanent improvements to the genetic makeup of irradiated plants. Since then, studies related to breeding mutations have grown, as efforts have been made to expand and improve crop productivity and quality. Stadler's discovery began with x-rays on corn and barley and later extended to the use of gamma-rays, thermal, and fast neutrons in crops. Radiation has since been shown to be an effective and unique method for increasing the genetic variability of species, including rice. Numerous systematic reviews have been conducted on the impact of physical mutagens on the production and grain quality of rice in Southeast Asia. However, the existing literature still lacks information on the type of radiation used, the rice planting materials used, the dosage of physical mutagens, and the differences in mutated characteristics. Therefore, this article aims to review existing literature on the use of physical mutagens in rice crops in Southeast Asian countries. Guided by the PRISMA Statement review method, 28 primary studies were identified through a systematic review of the Scopus, Science Direct, Emerald Insight, Multidisciplinary Digital Publishing, and MDPI journal databases published between 2016 and 2020. The results show that 96% of the articles used seeds as planting materials, and 80% of the articles focused on gamma-rays as a source of physical mutagens. The optimal dosage of gamma-rays applied was around 100 to 250 Gy to improve plant development, abiotic stress, biochemical properties, and nutritional and industrial quality of rice.

MeSH terms: Plant Breeding; Mutagens*; Mutation; Crops, Agricultural/genetics
Fulltext First record of the genus Passiena (Araneae, Lycosidae) from China, with the first description of the male of P.spinicrus Thorell, 1890 from Malaysia

Tan B, Irfan M, Zhang ZS, Wang LY

Zookeys, 2023;1182:1-9.
PMID: 37868119 DOI: 10.3897/zookeys.1182.109532

The genus Passiena is recorded for the first time from China with Passienaduanisp. nov. (♂♀) from Guangxi described here. In addition, the male of P.spinicrus Thorell, 1890 is described for the first time based on a specimen from Malaysia and colour photographs of freshly collected material are also presented. Detailed morphological descriptions, photographs, genital illustrations, and a distribution map for the two species are provided.
Fulltext Digital technology usage among older adults with cognitive frailty: A survey during COVID-19 pandemic

Md Fadzil NH, Shahar S, Singh DKA, Rajikan R, Vanoh D, Mohamad Ali N, et al.

Digit Health, 2023;9:20552076231207594.
PMID: 37868158 DOI: 10.1177/20552076231207594

OBJECTIVE: The research aimed to study digital divide by determining the usage of digital technology among older adults with cognitive frailty (CF) in Malaysia.
METHODS: The dataset was obtained from the AGELESS trial screening phase conducted from October 2021 to March 2022, involving 476 community-dwelling Malaysian older adults (67.7 years old ± 6.1). Digital technology usage was assessed and CF was determined using Fried's criteria and Clinical Dementia Rating. A binary logistic regression was used to determine the sociodemographic factors associated with digital technology use among older adults with CF.
RESULTS: The findings suggest a digital divide between older adults with CF and robust in Malaysia. CF individuals (72.1%) were less likely to utilise digital technology, mainly smartphone than robust older adults (89.6%). More than 70% of older people owned social media on their smartphones, namely, WhatsApp. The most frequent online activities in both groups were family interaction and obtaining current news. CF older adults were less likely to play games on their smart devices. Usage of digital technology was more common among male, younger age, attained formal education more than 6 years, had a higher monthly household income, and robust participants.
CONCLUSIONS: The usage of digital technology was inversely related to CF status. CF older adults were less likely to integrate digital technology into their daily living compared to robust even though they were familiar with it. The use of digital technology should be reinforced among female, advanced age, widowers/divorcees without formal education and those from lower- or middle-income statuses, and cognitively frail older people.
Obesogenic Environment in the medical field: First year findings from a five-year cohort study

Andoy-Galvan JA, Sriram S, Kiat TJ, Xin LZ, Shin WJ, Chinna K

F1000Res, 2023;12:550.
PMID: 37868299 DOI: 10.12688/f1000research.125203.1

Background: Doctors with a normal BMI and healthy living habits have shown to be more confident and effective in providing realistic guidance and obesity management to their patients. This study investigated obesogenic tendencies of medical students as they progress in their medical studies. Methods: A cohort of forty-nine medical students enrolled in a five-year cohort study and was followed up after one year. At the initiation of the cohort, socio-demography and information on anthropometry, accommodation, eating behavior, stress and sleeping habits of the students had been recorded. Follow-up data was collected using a standardized self-administered questionnaire. Results: Thirty-seven percent of the students in the cohort are either obese or overweight in the one-year period.. A year of follow-up suggests that there is an increase in BMI among the male students (P=0.008) and the changes are associated with changes in accommodation (P=0.016), stress levels (P=0.021), and sleeping habits (P=0.011). Conclusion: Medical education system should seriously consider evaluating this aspect in the curriculum development to help our future medical practitioners practice a healthy lifestyle and be the initiator of change in the worsening prevalence of obesity worldwide.

MeSH terms: Humans; Male; Surveys and Questionnaires; Students, Medical*; Cohort Studies; Overweight/epidemiology
Supporting validity: steps to contextualise applications for technology and assessment, for learning

Kemp S, Goddard VCT, Boursicot K, Fuller R, Nadarajah VD

MedEdPublish (2016), 2023;13:37.
PMID: 37868340 DOI: 10.12688/mep.19688.1

In the paper, the authors offer perspectives on the uses of technology and assessment, that support learning. The perspectives are viewed through validity (from the field of assessment) as a framework and they discuss four aspects of an interconnected technology, learning and assessment space that represent theory informed, authentic practice. The four are: 1) integrated coherence for learning, assessment and technology; 2) responsibilities for equity, diversity, inclusion and wellbeing; 3) sustainability; and 4) balancing resources in global contexts. The authors propose steps and considerations for medical and health professions educators who need to contextualise applications for technology, learning and assessment, for positive impact for learners, faculty, institutions and patient care.
Fulltext Scrub Typhus Presenting As Acute Febrile Illness With Splenic Infarct: A Rare Manifestation

Kamra N, Jagadeesan S, Singh R

Cureus, 2023 Sep;15(9):e45622.
PMID: 37868404 DOI: 10.7759/cureus.45622

Scrub typhus is a mite-borne infectious disease endemic in India, Korea, China, Japan, Taiwan, Pakistan, Malaysia, Thailand, and Australia. It has a multitude of clinical manifestations ranging from mild symptoms like headache, myalgia, anorexia, fever, and rash to severe multiorgan failure. It can also lead to several complications, including pancreatitis, hepatitis, myocardial infarction, and cerebral infarction. A few cases of splenic infarction are also reported. We report a rare case of a 40-year-old female presenting with fever and left upper quadrant abdominal pain of acute onset. She is diagnosed serologically with scrub typhus using enzyme-linked immunosorbent assay (ELISA) after ruling out other infectious causes, including other tropical diseases. Abdominal computed tomography revealed splenic infarction attributed to scrub typhus after excluding other etiologies. She improved after a course of doxycycline and was advised to follow up. Hence, a splenic infarct should be suspected in a patient with scrub typhus complaining of acute left hypochondriac pain.
Fulltext A Case of Actinomycosis of the Nasopharynx

Tumaisuri D, A F, Razali F, Husain S

Cureus, 2023 Sep;15(9):e45710.
PMID: 37868511 DOI: 10.7759/cureus.45710

Actinomycosis is a progressive granulomatous infection caused by the bacteria Actinomyces israelii. Classically, the three most common clinical forms are cervicofacial, thoracic, and abdominopelvic. On the contrary, nasopharyngeal actinomycosis is considered to be a rare clinical disease, and its occurrence is extremely low. The infection can take place without any preceding infection or on immunocompromised status. A 25-year-old male with no previous medical history presented with persistent nasal congestion and rhinorrhea. A nasal endoscopy examination revealed an unclearly demarcated nasopharyngeal mass, and a complete microbiology and pathology analysis showed actinomycetes colonies. After two weeks of oral Augmentin therapy, the patient's illness was completely eradicated. Diagnosis of nasopharyngeal actinomycosis is exceptionally crucial, and with early treatment of appropriate antibiotic therapy, the prognosis is excellent. Careful follow-up after adequate treatment as the possibility of frequent relapse is common.
Fulltext Alcohol-induced liver injury in signalling pathways and curcumin's therapeutic potential

Subramaniyan V, Lubau NSA, Mukerjee N, Kumarasamy V

Toxicol Rep, 2023 Dec;11:355-367.
PMID: 37868808 DOI: 10.1016/j.toxrep.2023.10.005

Confronting the profound public health concern of alcohol-induced liver damage calls for inventive therapeutic measures. The social, economic, and clinical ramifications are extensive and demand a comprehensive understanding. This thorough examination uncovers the complex relationship between alcohol intake and liver damage, with a special emphasis on the pivotal roles of the Toll-like receptor 4 (TLR4)/NF-κB p65 and CYP2E1/ROS/Nrf2 signalling networks. Different alcohol consumption patterns, determined by a myriad of factors, have significant implications for liver health, leading to a spectrum of adverse effects. The TLR4/NF-κB p65 pathway, a principal regulator of inflammation and immune responses, significantly contributes to various disease states when its balance is disrupted. Notably, the TLR4/MD-2-TNF-α pathway has been linked to non-alcohol related liver disease, while NF-κB activation is associated with alcohol-induced liver disease (ALD). The p65 subunit of NF-κB, primarily responsible for the release of inflammatory cytokines, hastens the progression of ALD. Breakthrough insights suggest that curcumin, a robust antioxidant and anti-inflammatory compound sourced from turmeric, effectively disrupts the TLR4/NF-κB p65 pathway. This heralds a new approach to managing alcohol-induced liver damage. Initial clinical trials support curcumin's therapeutic potential, highlighting its ability to substantially reduce liver enzyme levels. The narrative surrounding alcohol-related liver injury is gradually becoming more intricate, intertwining complex signalling networks such as TLR4/NF-κB p65 and CYP2E1/ROS/Nrf2. The protective role of curcumin against alcohol-related liver damage marks the dawn of new treatment possibilities. However, the full realisation of this promising therapeutic potential necessitates rigorous future research to definitively understand these complex mechanisms and establish curcumin's effectiveness and safety in managing alcohol-related liver disorders.
Fulltext Editorial: Neuroinflammation and neurodegeneration from bench to bedside

Mohamed WMY, Kwakowsky A

Front Neurol, 2023;14:1296760.
PMID: 37869152 DOI: 10.3389/fneur.2023.1296760
Fulltext Editorial: Global surgery: the next Frontier in global public health

Henry JA, Wong LY, Ameh E, Yip CH, Hill A

Front Public Health, 2023;11:1293880.
PMID: 37869182 DOI: 10.3389/fpubh.2023.1293880
MeSH terms: Ophthalmology*; Public Health*; Global Health; World Health Organization
Fulltext Implementation of a psychomotor vigilance test to investigate the effects of driving fatigue on oil and gas truck drivers' performance

Al-Mekhlafi AA, Isha ASN, Al-Quraishi MS, Kanwal N

Front Public Health, 2023;11:1160317.
PMID: 37869200 DOI: 10.3389/fpubh.2023.1160317

INTRODUCTION: Driving fatigue has been shown to increase the risk of accidents and potentially fatal crashes. Fatigue is a serious risk that some drivers do not take seriously. Previous studies investigated the effects of driving fatigue in the Malaysian oil and gas transportation industry by employing survey questionnaires. However, they did not explain the behavior of fatigue. Besides, these results required validation by a more reliable method that can describe how fatigue occurs.
METHODS: Thus, in this study, we used the Psychomotor Vigilance Test (PVT-192) and a short survey to address driving fatigue behavior and identify the influences of driving fatigue on driving performance in real life (on the road) with actual oil and gas tanker drivers. The total participants in the experimental study were 58 drivers.
RESULTS: For the analysis, a Wilcoxon Signed Ranks Test, Z value and Spearman's rho were used to measure the significant difference between the pre and post-tests of PVT and the correlation between the fatigue variables and driving performance.
DISCUSSION: During the experiment's first and second days, this study's results indicated that driving fatigue gradually escalated. Likewise, there was a negative correlation based on the test of the relationship between the PVT data and the driving performance survey data. Additionally, the drivers suffer from accumulative fatigue, which requires more effort from the transportation company management to promote the drivers awareness of fatigue consequences.

MeSH terms: Accidents, Traffic*; Humans; Surveys and Questionnaires; Transportation; Wakefulness; Motor Vehicles*
Fulltext Highly effective ashless and non-corrosive dimercaptobenzothiadiazole as multifunctional lubricant additives in naphthenic base oil

Ong CL, Lai YC, Heidelberg T, Tang WK, Lee VS, Khaligh NG, et al.

RSC Adv, 2023 Oct 18;13(44):30733-30742.
PMID: 37869389 DOI: 10.1039/d3ra05692a

The conventional medium chain chlorinated paraffin (MCCP) and zinc dialkyl dithiophosphate (ZDDP) additives have greatly enhanced the extreme pressure (EP) and anti-wear (AW) performance of the metalworking fluids. However, chlorine- and zinc-containing additives are restricted in use due to eco-toxicity issue. Herein, ashless and non-corrosive dimercaptobenzothiadiazole derivatives, namely bis-2,5-benzylsulfanyl-[1,3,4]thiadiazole (BBST) and bis-2,5-octylsulfanyl-[1,3,4]thiadiazole (BOST) consist of three sulfur atoms have been synthesized and evaluated. The performance of BBST shows a weld load (PD) of 3089 N and AW value of 5 mm2, which represents an improvement of 3.1 and 7.4 folds over naphthenic base oil (NBO). In addition, BBST also outperformed BOST, MCCP, and ZDDP in terms of its weld load and AW properties. Based on XPS analysis and molecular electrostatic potential maps (MEPS), BBST exhibits superior tribology performance due to the interaction between the sulfur (S), nitrogen (N), and π-electrons of the benzene ring with the metal surface. The formation of FeS, Fe2O3 and Fe⋯N coordinate bonds contributes to the creation of an excellent tribofilm.
Multi-objective test selection of smart contract and blockchain applications

Alkhazi B, Alipour A

PeerJ Comput Sci, 2023;9:e1587.
PMID: 37869450 DOI: 10.7717/peerj-cs.1587

The ability to create decentralized applications without the authority of a single entity has attracted numerous developers to build applications using blockchain technology. However, ensuring the correctness of such applications poses significant challenges, as it can result in financial losses or, even worse, a loss of user trust. Testing smart contracts introduces a unique set of challenges due to the additional restrictions and costs imposed by blockchain platforms during test case execution. Therefore, it remains uncertain whether testing techniques developed for traditional software can effectively be adapted to smart contracts. In this study, we propose a multi-objective test selection technique for smart contracts that aims to balance three objectives: time, coverage, and gas usage. We evaluated our approach using a comprehensive selection of real-world smart contracts and compared the results with various test selection methods employed in traditional software systems. Statistical analysis of our experiments, which utilized benchmark Solidity smart contract case studies, demonstrates that our approach significantly reduces the testing cost while still maintaining acceptable fault detection capabilities. This is in comparison to random search, mono-objective search, and the traditional re-testing method that does not employ heuristic search.
Fulltext Semantic visual simultaneous localization and mapping (SLAM) using deep learning for dynamic scenes

Zhang XY, Abd Rahman AH, Qamar F

PeerJ Comput Sci, 2023;9:e1628.
PMID: 37869467 DOI: 10.7717/peerj-cs.1628

Simultaneous localization and mapping (SLAM) is a fundamental problem in robotics and computer vision. It involves the task of a robot or an autonomous system navigating an unknown environment, simultaneously creating a map of the surroundings, and accurately estimating its position within that map. While significant progress has been made in SLAM over the years, challenges still need to be addressed. One prominent issue is robustness and accuracy in dynamic environments, which can cause uncertainties and errors in the estimation process. Traditional methods using temporal information to differentiate static and dynamic objects have limitations in accuracy and applicability. Nowadays, many research trends have leaned towards utilizing deep learning-based methods which leverage the capabilities to handle dynamic objects, semantic segmentation, and motion estimation, aiming to improve accuracy and adaptability in complex scenes. This article proposed an approach to enhance monocular visual odometry's robustness and precision in dynamic environments. An enhanced algorithm using the semantic segmentation algorithm DeeplabV3+ is used to identify dynamic objects in the image and then apply the motion consistency check to remove feature points belonging to dynamic objects. The remaining static feature points are then used for feature matching and pose estimation based on ORB-SLAM2 using the Technical University of Munich (TUM) dataset. Experimental results show that our method outperforms traditional visual odometry methods in accuracy and robustness, especially in dynamic environments. By eliminating the influence of moving objects, our method improves the accuracy and robustness of visual odometry in dynamic environments. Compared to the traditional ORB-SLAM2, the results show that the system significantly reduces the absolute trajectory error and the relative pose error in dynamic scenes. Our approach has significantly improved the accuracy and robustness of the SLAM system's pose estimation.

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